A radiographic fluoroscopic X-ray table is one capable of being used for radiographic X-ray procedures and for fluoroscopic X-ray procedures. In a typical radiographic procedure, X-ray film is positioned, in the table body below the tabletop in alignment with an X-ray tube suspended over the table and generally supported by a roller track attached to the ceiling or other means independent from the table itself. The X-ray tube and the film are positioned such that a patient lying on the table will have that portion of his body to be X-rayed located in the path of the X-ray beams directed from the tube towards the film.
The radiographic fluoroscopic table has the additional feature of an X-ray tube located in the table body beneath the table's top and a spot film device attached to the table and located over the surface. The spot film device contains a film cassette which records the X-ray image of the patient produced by the X-ray tube located in the table. The technician has the option of removing the film cassette from the path of the X-ray beams and permitting the beams to pass through an image intensifier mounted on the spot film device. After passing through the image intensifier, the beams are coupled into an optical distributor which can distribute the image among any of three cameras also mounted on the spot film device; a television camera which is connected to a monitor located in the X-ray room a spot film camera which contains 105 millimeter X-ray film and is capable of taking up to 12 frames per second, and a 35 millimeter cine camera which takes up to 70 frames per second of the X-ray image being transferred through the image intensifier and optical distributor.
The television camera is useful because it allows the technician for the X-ray table to monitor the X-ray images and select the right portion of the body or the right instant at which an X-ray should be taken. The spot film camera adds the additional option of being able to monitor using a television camera while taking X-ray pictures. While the film in the spot film camera is smaller than that contained in the film cassette, it is still sufficiently large to give adequate resolution for most X-ray analysis.
The 35 mm cine camera adds the additional option of being able to record dynamic events on X-ray film. However, due to the fact that the film is much smaller, resolution is greatly decreased and the quality of the picture is much lower than X-ray pictures taken using a film cassette or a spot film camera. The 35 mm cine camera is generally used only for specialized procedures such as heart studies. A spot film device which includes all of the above three cameras is called a three port system. Spot film devices are also produced which include only one or two of the three camera options and are known respectively as one port and two port systems.
The spot film device is supported over the table by a fluoroscopic staging structure. This staging structure has heretofore included a carriage system located underneath the table's upper surface, comprising a longitudinal carriage and a transverse carriage which respectively allows the spot film device to travel the length and width of the X-ray table. The X-ray tube in the table is attached to the carriage structure such that it is always located directly below the spot film device and aimed at the image intensifier mounted thereon.
The fluoroscopic staging apparatus also includes a vertical carriage which allows the spot film device to be lowered or raised with respect to the table surface. This vertical carriage is counterbalanced using cables and pulleys with weights located in the table itself so as to allow the spot film device to be raised and lowered manually with minimum effort. In addition, the entire fluoroscopic staging apparatus, including carriages and spot film device, must be counterbalanced along the longitudinal axis of the table, because the table, of which it is part, tilts with respect to the horizontal along its longitudinal axis. For the sake of clarity, the term "vertical", as used herein, with respect to the radiographic system shall mean vertical with respect to the table surface to allow for X-ray tables which may tilt.
The problem in the past has been to adequately support a three port spot film device on an X-ray table with a transverse carriage and a longitudinal carriage. The transverse carriage is conventionally attached to the longitudinal carriage by a system of roller bearings and track in the longitudinal carriage. The longitudinal carriage in turn is attached to the table by means of a bearing and track system which permits movement in the longitudinal direction with respect to the table. With a three port spot film device, the use of both a transverse carriage and a longitudinal carriage has resulted in impermissable deflection in the staging structure. Using both of these carriages in the table, each carriage having its own roller and track system, there has been insufficient rigidity in the staging apparatus due to movement or "give" in the track assemblies. Under the load, carried by the carriage system, which is usually over 400 pounds, the fluoroscopic staging apparatus deflects beyond permissible ranges. The problem is particularly acute when the table is of the type which can tilt .+-. 90.degree. from horizontal. To overcome this problem, an overhead suspension system supported by the ceiling above the table has heretofore been employed to partially support the weight of a three port spot film device, thereby decreasing deflection. In addition to the resulting awkward installation of the table within the room, however, the longitudinal and transverse movement of the staging requires the movement of a substantial mass of material in the transverse longitudinal carriages requiring, in turn, substantial effort on the part of the technician.